The present invention relates generally to collision avoidance systems or blind spot detectors and more particularly to a blind spot detector utilizing polarametric transmitters with steerable beams.
Known collision avoidance systems including blind spot detectors are known to include a transmitter which transmits a signal into the blind spot and a receiver which receives a reflected signal from an object in the blind spot. Upon receiving the reflected signal, the blind spot detector indicates to the driver that a vehicle or other object is located in the blind spot.
For example, when a vehicle is about to change lanes, the collision avoidance system indicates to the driver that another vehicle is adjacent the driver""s vehicle. Other collision avoidance systems detect the presence of an object to the rear of the vehicle, such as when the vehicle is in reverse. Currently known blind spot protectors are expensive in order to provide reliable indications of the presence of an object in the blind spot.
The present invention provides a collision warning system or xe2x80x9cblind spot detection systemxe2x80x9d utilizing circularly polarized transmitters and receivers. The blind spot detection of the present invention provides accurate and reliable indications of the presence of objects (such as nearby vehicles) at low cost.
The blind spot detection system generally includes a transmitter and antenna system which generates a circularly polarized signal into the blind spot. A receiver, also mounted on the vehicle, receives a reflection of the circularly polarized signal. Upon reflection of the circularly polarized signal from a conducting object (such as a vehicle) the polarity of the reflected signal is reversed. The receiver includes a circularly polarized antenna which is polarized opposite the polarization of an antenna of the transmitter. When the receiver receives a signal with the correct circular polarization, it is determined that an object is present in the blind spot.
In a preferred embodiment, the transmitter generates a steerable signal which the transmitter sweeps along a horizontal plane to increase the coverage of the blind spot. In addition, the transmitter sweeps in a vertical plane to discriminate an adjacent object (i.e., to discriminate between a vehicle and a guard rail). If a vehicle is detected in the blind spot, an indication is provided to the driver, such as an audible warning and/or visual indicator, such as a light.
The system also preferably provides a warning to an adjacent vehicle. Preferably, a visual indicator, such as a light mounted in the side view mirror, is illuminated when the presence of the vehicle in the blind spot is detected and there is an indication (such as a turn signal switch activation) that the first vehicle is going to change lanes.
The blind spot detector could also be directed toward the rear of the vehicle to detect obstacles while the vehicle is in reverse. Similarly, it could be directed in front of the vehicle for low visibility situations, such as dense fog.